Center-square.



UNITED STATss PATENT OFFICE.

KARL O. MUEHLBERG, OF` BRADDOCK, PENNSYLVANIA.

Geuren-SQUARE.

SPECIFICATIQN forming part of Letters Patent No. 694,774, dated March 4,1902.

Application filed July 5,1201. Serial No, vtl 7,171. (No model.) i

To all whom it may concern: Y

Be it vknown that 1, KARL O. MUEHLBERG, a resident of Braddock, in the county ot Allegheny and State of Pennsylvania, have invented a new and useful Improvement lin Center-Squares; and I do hereby declare the following to be a full, clear, and exactdescription thereof. Y

My invention relates to center -squaresg and its object is to provide a center-square with an adjustable arm or rule7 so as to compensate for wear or defects in construction,

thereby insuring that the center line will al-A ways be accurately'drawn and also` permitting the drawing of lines parallel to said center line, to provide acenter-square which can be centered either on the outside of a solid body or the inside of a circular hole, and to provide a center-square which can be used either asa T-square, as a try-square, asv

a parallel or lcircular Vscribe, or asa graduated rule. y

In the accompanying drawings, Figure l is a plan view of my improved center-square. Fig. 2 is a side view of the same. Fig. 3 is a longitudinal section ou the line 3 3, Fig. 1.

Fig. fl is a ltransverse section on the lined 4, Fig. 1; 'and Fig. 5 is a bottom plan view.;

My center-square comprises the body 1, which is provided on its forward edge with the centering-angle 2. Mounted on the body is the arm 3, which normally is in such position that its edge 4c exactly `divides the centering-angle 2, so that i when thef centeringangle 2 is placed against the outside'of acircular object the edge e of the arm will form the center line of said body, as will bereadily understood. The body 1 is provided on its upper surfacefwith a kgroove 6, extending across thel same at right angles to the center line of the angle 2, and the said body is provided withthe slot or opening 7, which extends almost entirely across the body, said slot being in the central line of the groove 6 and havingthe lower'edge of its walls `beveled od, as shown at 8. Mounted in the groove 6 is aslide 9, provided with the depending block 10, which projects down into the groove 7 and which is provided witha screw-threaded hole for receiving the adjusting-screw 11. This screw is mounted in the portions 12 of the body at the end of the Y .groove7 and isprovided with milled heads 13 at both ends, whereby the screw can be turned to adjust the slide 9 laterally on the 'body 1 ofthe square. Also moving in the groove? is a block 14, which is provided with beveled projections15 on its edges which are adapted to 'engage the beveled walls 8 of the groove 7 This block is provided with ahole which is sufficiently large to allow the screw 11 topass freely therethrough. On the upper side of the block is formed or suitably attached a screw 16, extending up through an opening in the slide@ and which receives the milled nut 17. By means `of this nut the screw 16 and block 14 can be drawn upward, thereby bringing the projections 15 of the block against the beveled walls 8 of the groove 7, thereby locking the slide in place on the body 1 in any position to which it may have been moved by the adj listing-screw. 11. Thisslideis provided on its ,Upper side;

' with a suitable abutment-such, for instance, v as the two pins 19,which are parallel to the center line of the angle 2-against which 'abutmentthe edge L.tof the arm 3 bears. This arm is clamped tothe slide'by the clamping-,plate 20. and screw 21, said plate having one end bent vdownward and bearing on the upper face of the slide and havingits opposite end provided' with a bead orrib 22, Iittingin a groove 23 of the. arml 3. By means of the abutment 19 and clamping-plate20 the arm 3 is secu red firmly to the slide 9, with its edge 4 parallel to the centerline of theaugle 2, and by means.

of the'screw 11 the slide 9, together withV the arm3, may be adjusted laterally, so as to 'y bring the edge f4 of the armto coincide with the'center line of the angle 2 or tolie parallel thereto at any desired distance therefrom.

AWrhenfthus adjusted,the arm and slide are clamped inplace by means of the nut 1'?.`

Vthe entire body of the center-square then the projecting horns 25 will be caused to bear In case the hole against the inside of the hole or tubular body, these horns being accurately formed with reterence to the angle 2. The abutment, such as the pins 24, must of course also be accurately placed with reference to this angle. These pins 24 will also serve, in conjunction witha scribing-point, such as the pointed screw 26 in the outer end of the arm 3, as an ordinary parallel scribe-that is, by causing the said pins 24 to bear against the edge of any object and moving the instrument parallel with the edge of the body a line will be formed by the point 26 parallel with said edge. To serve as a circular scribe, the point 26 is used in conjunction with a point such as the pointed screw 27 in the body. The arm 3 is adjusted in the clamp 2O until the desired distance between vthe points 26 and 27 is secured, and then by ,using one of these points, such as the point 27, as a center the other point can be used as a scribe to describe an arc about said center.

The rear edge 28 of the body is formed straight and at right angles to the center line of the angle 2, so that said-edge 28, together with the edge 4 of the arm 3, can be used either as a T-square or as a try-square. The ends of the body are also formed straight and at right angles to the edges of the slide 9, and the edges of this slide are graduated,as shown so that the distance to which the arln 3 is adjusted from the center line of the angle 2 can be readily ascertained. The slide 9 may be.

adjusted sofar beyond either end of the body that the edge thereof, together with the end 29 of the body, will form a very small square, and the graduations o n the edge of the slide will enable the square to be formed of any dimension desired. `The arm 3 is provided with the graduations 30, thereby enabling it to beused as an ordinary graduated rule.

It will thus be seen that my center-square is so constructed that it can be used to-center either on the outside of circular bodies or from the inside of circular tubular bodies or holes, that it can be used either as a trysquare, T-square, a parallel scribe or circularscribe, and that the adjustment ofthe arm 3 by means of the slide 9 enables the edge 4 of said arm to be brought into exact coincidence with the center line of the angle 2, thereby compensating for wear or defects in construction. and making the instrument perfectly accurate, or that by these means the said arm may be` adjusted to any desired distanceto either side of the center line, thereby enabling the user to lay off Work wherein the lines are parallel to but at one side of the center line of a circular body.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. In a center-square, the combination with a body provided with a centering-angle and-a transverse slot therethrough, of a slide mounted thereon, said slide being provided with a screw-threaded block projecting through the slot in the body, a screw mounted in said body and passing through said block for adjusting the slide laterally, and an arm carried by the slide.

2. In a center-square, the combination with a body provided with a centering-angle and a transverse slot therethrough,of aslide mounted thereon, said slide being provided with a screw threaded block projecting down p through the slot in the body, a screw mounted in said body and passing through said block for adjusting the slide laterally, means for clamping the slide inl its adjusted position to the body, and an arm carried by the slide.

3. In a center-square, the combination with a body provided with a centering-angle and a transverse slot therethrough, said slot being provided with beveled side walls, of a slide mounted on the bod-y, said slide being provided with a screw-threaded block projecting through the slot in the body, a screw mounted in said body and passing through said block for adjusting the slide laterally, an arm carried by the slide, a block moving in the slot of the body andhaving beveled faces engaging the beveled side walls ot the slot and provided with an enlarged hole'through which the screw passes,vsaid block being provided with a screw-threaded shank extending up through the slide, and a nut engaging said screw-threaded shank for clamping the slide to the body.

In testimony whereof I, the said KARL O. MUEHLBERG, have hereunto set my hand.

KARL 0. MUEHLBERG. Vitnesses:

JAMES I. KAY, WALTER FAMARiss. 

